Technical Field
The disclosure is related to a three dimensional printing technique, and particularly to a sensing device utilized for sensing a cross section layer of a 3D printing object.
Background
Three-dimensional (3D) printing technology is considered as a Computer-Aided Manufacturing-shape (CAM), which is developed and utilized in industrial manufacturing-shape for rapidly producing 3D products. In general, the 3D printing is a series of design concepts of rapid prototyping (RP) technology. The principle of 3D printing is to form a cross-section of an object in X-Y plane via scanning and then stack each cross-section layer in a Z coordinate layer by layer, so as to manufacture a 3D printing object by a layer stacking means. Therefore, the 3D printing technology may be adapted for manufacturing-shape 3D printing objects having any geometric shape, and complex parts would demonstrate a more superior RP technology, and can significantly save manufacturing-shape time.
In the 3D printing technology, each 3D printer desires a height of each cross-section layer of the object dispensed by a printing head of the 3D printer would be the same after the solidification of the dispensed material, so that the subsequent cross-section layer may be dispensed based on prior layer. FIG. 1 is a schematic diagram illustrating a 3D printer. As illustrated in FIG. 1, a computer 110 is coupled to a 3D printer 100 and prints a cross-section layer 140 of a 3D model designed by the CAD software through a controller 120 and a printing head 130. Since material utilized by the 3D printer 100 is usually solid material which cures from fluid state, and the ink droplets formed by the material in fluid state have surface strain between each other, micro gaps would occur between the dispensed materials. In addition, dispensing rate, printing rate, and other problems may occur due to the ambient temperature while dispensing of the material by the printing head 130, which presents a difficulty for the each cross-section layer 140 of the object to be planar having a predetermined height H. As a result, the surface of the printed object may be recessed and not flat after stacking of a plurality of cross-section layer of the object.
Thus, there is a roller 150 (also referred as a planarizer) in the 3D printer 100 to flatten the cross-section layer of the object 140. However, the height of each cross-section layer 140 may be different. The 3D printer 100 has to learn when or at which height would the roller 150 contact the cross-section layer 140, so as to perform a planarization process. Thus, how to detect when the roller 150 contacts the cross-section layer 140 of the object is one of the difficulties in the 3D printing technology faces.